FIG. 3 shows a conventional electrical double-layer capacitor cell. In FIG. 3, numerals 1 and 2 denote collecting electrodes, 3 and 4 gaskets, 5 a separator, and 6 and 7 paste-like polarizing electrodes.
The collecting electrodes 1 and 2 are formed of conductive rubber sheets, and the gaskets 3 and 4 are formed of insulating rubber. The paste-like polarizing electrodes 6 and 7 are made of paste-like active carbon powder formed by immersing dilute sulfuric acid in the powder. For the separator 5, a porous plastic film which passes ions, but which does not pass the active carbon particles, is used.
In order to make good contact between the active carbon particles to and to make good contact between the collecting electrode 1 and the paste-like polarizing electrode 6 and between the collecting electrode 2 and the paste-like polarizing electrode 7 pressure is applied on the collecting electrodes 1 and 2. In order not to be destroyed by this pressure, the materials for the collecting electrodes 1 and 2 and for the gaskets 3 and 4 should be such which have elasticity.
In order to make the capacity of such an electrical double-layer capacitor cell large, it is necessary to increase the specific surface area (usually, 1000 to 2000 m.sup.2 /g) of the active carbon forming the polarizing electrode, and to make the bulk density in the capacitor case when it has been filled large.
On the other hand, since the polarizing electrode is difficult to handle in such a state when it is in a paste-like form, there has been proposed a method in which the polarizing electrode is sintered to become a solid plate-like form (for example, the official publication of the Japanese Patent Application Laid-Open No. 292612/1987). When it is formed in a solid plate-like state, there is also the advantage that the bulk density is enhanced and the capacity is increased, and additionally, the contact of the active carbon particles to each other becomes denser to decrease the contact resistance.